The core virology laboratory will be responsible for performing protocol mandated virology testing. This will serve the ACTU in this institution as well as other ACTG units without virology core laboratories. HIV, CMV, EBV, VZV, and HSV serologic studies will be performed at baseline and thereafter as mandated by the clinical protocol. Primarily, initial baseline virology determinations will be done before the initiation of therapy, and at frequent intervals thereafter, these will include virus isolations and HIV serum P-24 Ag determinations. HIV isolations will be from peripheral blood, unless protocol mandates otherwise. HIV plasma viremia may be determined, when indicated, as a potential marker of antiretroviral therapeutic efficacy. The virology core will also isolate and quantify other opportunistic viruses that commonly infect HIV patients, particularly cytomegalovirus (CMV), herpes simplex virus (HSV), and adenovirus. Quantitative CMV urine cultures are available for use as a marker of anticytomegaloviral therapeutic efficacy. All isolates recovered from patients on specific antiviral therapy will be stored for use, as needed, for antiviral resistance testing. Rapid CMV culture recovery may be facilitated using the shell vial centrifugation method. Sensitivity testing of patient derived viral isolates to antiviral compounds (e.g. ganciclovir-resistant CMV and acyclovir-resistant HSV) will be done as needed. Measurement of other surrogate markers of HIV markers as gp120, nef protein, neopterin, B2 microglobulin, and C1q and other markers as indicated by study protocols. Moreover, the laboratory will continue to be involved in the development and evaluation of novel virology diagnostic tools as they become available and in the modification of existent methodologies to increase their sensitivities and specificities. The laboratory will also participate in the quality assurance program established by the ACTG in order to standardize the results obtained.